Components for permanent removable and adjustable dentures and bridges

ABSTRACT

A locking cap for dental implants embedded in hard dental tissue, such as tooth stubs or bones. The locking caps are ovoidal in plan view and may be formed of materials, such as non-adherent polymers, that are rigid, but softer than the material of the dental implant.

This application is a continuation of U.S. patent application Ser. No.12/243,020, filed Oct. 1, 2008, now U.S. Pat. No. 7,985,071B2, which isa continuation application of Ser. No. 11/419,801, filed May 23, 2006,now U.S. Pat. No. 7,431,589, which application claimed the benefit ofthe filing date of U.S. provisional application No. 60/685,640, filed onMay 27, 2005, and U.S. patent application Ser. No. 10/746,674, filed onDec. 24, 2003, now U.S. Pat. No. 7,234,940B2.

FIELD OF THE INVENTION

The present invention relates to further improvements in dental implantstructures, and in particular to adjustable and/or modular, removablysecured dentures and dental bridges. i.e., oral, or dental prosthetics.A detailed background for this invention is provided in relatedInternational Publication number WO 02/28304 A2, published on 11 Apr.2002 (hereinafter the “Prior Case) and number WO2004/060189 A3,(hereinafter the “Prior Case II”), by the same inventor and applicant,the complete disclosures of which are incorporated herein by reference,including the specification and drawings.

BACKGROUND OF THE INVENTION

As shown in FIG. 1 of the Prior Cases, it is well known to firmly attachdentures to hard dental tissue, such as the jawbone 14 or tooth stubs byan implanted support, via prosthetic dental bridges 10; foundations 12for such bridges 10 are known. In particular, the dental bridge 10 maybe securely mounted to implanted screw posts 16, or other known securingmechanisms. Such foundations 12 are also described, for example, in U.S.Pat. Nos. 5,575,651 and 5,788,492. Other, more readily removable,dentures secured to implanted supports are shown, for example in U.S.Pat. Nos. 5,567,155 and 3,514,858.

The use of relatively slender implants to support foundations, describedin the first two patents identified above, and in the Prior Cases, wereoriginally considered suitable primarily as short term devices for useuntil the larger, “permanent” implants healed. One aspect of the presentinvention continues the earlier development and further understandingthat the slim implants can be used for substantially permanent, butremovable denture prostheses of various types. The devices andprocedures of the present invention avoid many of the problems ofearlier systems when worn for extended periods, which included the lackof capability for easy removal and replacement, and potential irritationto the patient because of the difficulty of obtaining a proper fit tothe jawbone and opposing teeth and gums, or to soft dental tissue.

Thus, a need continued to exist for a system which would permit theplacement of a long-lasting dental prosthesis in a patient's mouth bychairside techniques available to the family dentist. Such a systemshould provide components for mounting such prosthesis, which can befirmly secured to the hard dental tissue, such as the jawbone, in arelatively short time, but which can be adjusted or removed to beprophylactically cleaned or repaired at a later date, and which arereadily adaptable to the natural variations in the size and shape ofridges in jaw bones, so as to provide for more comfortable use of anydentures secured on such components, and which allows for multiplefittings and adjustments without damage to even the slender implants.

SUMMARY OF THE INVENTION

In accordance with a first aspect of the present invention, The existingor new denture prosthesis can be retrofitted with the advantageoussystem of this invention. The prosthesis can be removed from the mouthby the patient to be prophylactically cleaned daily, but is primarily isintended for fitting or refitting of the prosthesis without damage tothe implant posts, by the dentist.

The improvement of this invention is to be primarily used in denturesystems comprising anchoring implants and indexing guide pins that arepermanently implanted, bi-laterally, at the most posterior parts of thejaw. The channel forming the concave underside of a full, or partial,denture, for either the upper or lower jaw, can be lined with aresilient material, covering the hard denture form, and thus moreeffectively maintain the denture in the correct position whilecushioning the patient's dental ridge. Such a denture lining is intendedto provide for an improved grip on implants, and can be readilyresurfaced.

A chairside prosthesis foundation is also provided for securing to aplurality of anchored dental implants, in accordance with the PriorCases. Each implant useful in that situation has an intermediateplatform portion and an interconnectable top distal from the, preferablythreaded, implanted portion. The foundation can comprise modularcomponents, which can be supported by the intermediate implantplatforms, but which can be locked together by being encased in a resin,in a permanent relative juxtaposition. The locked together componentscan be removably connected to the implants, to enable subsequentadjustment of the prosthesis to fit a range of jaw ridge sizes or forcleaning or repair. As explained in the Prior Cases, such modularcomponents are secured in the jaw efficiently and relatively easily, andcan be adjusted at a later date, to conform to the many variations inthe size or shape of ridges in the jaw, rendering the prostheses morecomfortable to the wearer. As also explained in the Prior Cases, themodular components can be interconnected while secured to the implantsand are then reinforced and locked together by being encased by a cured,or hardened, resin composition, such as any of the self-curing dentalresins well known to dentists.

Both types of foundations, each referred to as a “splint”, provides abase upon which tooth forms/synthetic teeth can be supported. When thescrew shafts are implanted, temporary tooth forms can be created atchairside by a dentist, once a splint is in place, to provide a patientwith a prompt replacement of missing teeth, which are firmly butreplaceably connected to the implants. Immediately after placing theimplants, the splint serves to index the implanted screws so that theyare maintained in position without movement, to aid in the healingprocess with the jawbone, by allowing the bone to firmly grow around theimplants.

In one embodiment, shown in the Prior Case and Prior Case II, eachimplant shaft has a polygonal top driving portion, engaging an indexingmember which fits around and is held in a desired juxtaposition by thepolygonal top. The preferred indexing member has paired arms extendingoutwardly therefrom, forming slots there between. Connecting bars, orflexible bands, extend through the slots on each indexing member fromthe first of a series of such implants to the last of the series, thusinterconnecting the indexing members and thus anchoring the group ofimplanted screws together, to support each other in the desiredjuxtaposition. Each indexing member is in turn releasably secured to itsrespective implant shaft by a locking cap. To further enhance therigidity and support provided by the overall splint structure, the barsand the indexing members are encased in a resinous material, thusforming a unitary rigid structure, which can be separated as a unit fromthe series of implants.

In accordance with the improvement of the present invention, by formingthe locking caps from a material which is relatively soft compared tothe implant posts, and non-adherent to the encasing dental resin, suchas silicone or other polymeric non-adherent material, such as thepolyacetal Delrin, the locking cap can be readily and safely unscrewedfrom the implant, so that the foundation splint structure can be removedfrom the implants, once the implants are firmly set, i.e., fully healedto the bone, or earlier, if necessary. Any of the temporary or longerterm dentures can be thus supported on, and connected to the splint. Theretaining implants as improved by this invention, preferably have aspheroidal head or an ovoidal head, extending above the gum line, and aplatform substantially at the gum line and connected to the spheroidalor ovoidal head by a slender neck. A spheroidal head is one having agenerally circular shape from a top view, and an ovoidal head is onehaving a generally elongated, or ellipsoidal, shape from a top view.

The ovoidal head allows a secure fit for dentures for use on patientshaving very narrow, so-called “knife-edge”, gum ridges. The concavity onthe inner surface of the dentures for such patients must be molded tohave an especially narrow opening in order to obtain a firm fit oversuch narrow gum ridges. The use of the ovoidal head on the implantspermits firm and secure fitting for even the narrowest ridge, byaligning the major axis of the ovoidial head with the ridge.Alternatively, a denture for a wider ridge may be equally firmlysupported by aligning the ovoidal head transversely, or perpendicularly,to the gum ridge. This allows the ovoidal head to extend fully acrosseven the widest denture concavity and provide the required firm support.The widest dentures would be supported by aligning the major axisperpendicularly to the gum ridge, thus, the ovoidal head provides themost versatile use covering a wide range of denture sizes.

In accordance with the invention, damage during removal of the lockingcaps is further eased, while lessening the possibility of undulystressing or damaging the implant foundation, during the initial fittingperiod. In this invention, the non-adherent locking cap is formed of apolymer and has a skirt portion at one end, and a dome-shaped portion atanother end, having a spheroidal or ovoidal shape. The skirt portion ispreferably an annulus, concentric with the dome portion, and having aninternal diameter sufficient to surround any elements secured on theintermediate platform, but not greater than that of the platformdiameter, so that the skirt bottom presses against the top surface ofthe platform. Preferably, a non-circular or polygonal, top drivingportion is supported on the platform and in turn supports the threadedconnector. Most preferably, at best, two elongated circumferentialapertures are provided through the skirt, with relatively narrow skirtwall portions separating the two apertures. The apertures are preferablysymmetrical about the circumference. These non-adherent locking caps areespecially useful during the initial fitting period, when the fittingsand these caps must be removed from the implants several times.

The locking cap is threadedly secured to the interconnectable top of theimplant. When fitting the locking cap onto an implant, the externallythreaded interconnectable top mates with the internal threaded portionof the cap. To reduce the chances of unintentional loosening of the cap,the cap is locked in place using a curable resin, which is inserted intothe internal space within the skirt annulus in the locking cap. Theresin is preferably one that will cure and harden quickly after the capis screwed onto the implant, and is non-adherent to the locking cap.This hardened resin, portions of which extend into the apertures, willfurther secure the locking cap from rotational movement, which mightotherwise cause it to loosen by surrounding, for example, the polygonaldriving portion. The resin can be selected from among common curabledental resins, such as a polyacrylic or an epoxy polymer. When thelocking cap is to be removed, the usual torque level is applied by thedriving tool; the hardened resin in the apertures will tear the narrowstrips of polymer forming the intermediate strips between the apertures,when the torque is applied to the caps. These resins may be auto-curingor light-curing, both of which are commonly used in dentistry.Generally, these are non-adherent to many dental polymers, such asDelrin.

By providing cured resin through the apertures, the cap is locked inplace, but the cap can be readily torn at the ends of the apertures,under applied torque, thus, removing the lock without dislodging ormoving the implant part before healing is complete. The material betweenthe apertures can be made more likely to split in response to an appliedtorque by reducing the cross-sectional thickness of the material atthose intermediate portions. Preferably the apertures extend, in toto,at least about 50% of the circumference, and most preferably at leastabout 80% of the circumference. To avoid extrusion of the resin beyondthe apertures, before hardening, a thin, non adherent sleeve can beplaced over the apertures and around the skirt portion. The sleeve canhold the resin in place during curing. The sleeve is most preferablynon-adherent to the resin filling in the cap, such as a silicone, andalso can have a slight elasticity to improve holding and simplifyremoval after hardening.

In use, an auto-cure or light-cure resin is inserted into the inner cupof the skirt of the locking cap. The cap is firmly tightened in placeutilizing a U-shaped driver which fits within the aperture in thelocking cap. Preferably, the apertures extend around and down the sidesof the cap, and the U-shaped driver can conform to the downwardlyextending side slots. Alternatively, a standard straight or cruciformslot across the top of the dome is provided, to allow a screwdriver tobe used, or a polygonal indentation, for use, for example by an Allenwrench-type of driver. As the cap is screwed down, any excess curableresin material is forced outwardly, or upwardly, out of the cap, and canbe easily wiped away before the resin hardens. A silicone sleeve placedaround the apertures can be removed after the resin hardens.

The locking cap thus is held against rotation by the hardened resinsurrounding the polygonal driver part on the implant and extending intothe apertures of the skirt portion. The lower skirt portion, between theapertures, can be lifted out, or broken-up when exposed.

When it is desired to remove the cap, by applying sufficient torque tothe caps e.g. with the U-shaped driver in matching slots, the hardenedresin in the skirt will fracture the skirt wall portions, separating theapertures allowing, and the internally threaded portion of the cap andthe skirt will separate at the apertures, allowing it to be easilyunscrewed from the implant.

During the healing period, an interim prosthesis lined with the siliconematerial serves to lock the implants in place while providing an interimtooth replacement for the patient. That interim prosthesis will beremoved once healing is complete. This procedure may need to be repeateda number of times during the healing, and the following trials andfittings of the final customized prosthesis. This final prosthesis canbe constructed with the components described in, for example, U.S. Pat.No. 6,685,473 B2. After removal of the cap with the separated bottomsection, a new cap must be secured in place in the same manner, when theinterim prosthesis is replaced after the fitting.

The non-adhesive locking cap of this invention, is especially usefulduring the repeated fitting operations, because it is far less likely tostress or damage the thread of the, e.g., titanium, implant when beinginstalled onto the implant, or being removed therefrom.

In a preferred embodiment, a central opening extends through the cap,regardless of the shape of the head, so that it is open at both ends;this permits excess resin to escape out the top, as the cap is beingscrewed down, while being held in place onto the threaded portion. Thiscentral opening can be provided regardless of the shape of the cap head.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates, on a jaw model, a series of indexing and holdingimplants having the desired spheroidal head of this invention and bandednecks;

FIG. 1 a illustrates, on the jaw model of FIG. 1, a series of indexingand holding implants having the desired spheroidal head of thisinvention without the neck bands;

FIG. 2 illustrates, the jaw model of FIG. 1 with insert covers over theindexing implants;

FIG. 3 illustrates, the jaw model of FIG. 1; wherein the holdingimplants are covered by a half sheath;

FIG. 4 illustrates a detailed perspective view of the half sheath shownin FIG. 3;

FIG. 5 illustrates a top plan view of the spheroidal head of the holdingimplants of FIG. 1;

FIG. 6 illustrates, the jaw model of FIG. 3, wherein the holdingimplants are covered by a half sheath which is in turn covered by ametal reinforcing frame;

FIG. 7 illustrates an elevation view of a spheroidal-headed implant forthe present invention, as shown in FIG. 1;

FIG. 8 illustrates a front view of a splint being applied to the jaw,over the holding implants; and

FIGS. 9A-I illustrate the procedure for forming a completed splint ordental prosthetic bridge in accordance with the present invention.

FIG. 10 illustrates a locking screw cap made of a structural,nonadherent polymer, such as the polyacetal Delrin, to secure theprosthesis to the implant;

FIG. 11 illustrates a single tooth prosthesis anchored to an implant;

FIG. 12 illustrates the skeleton of a prosthesis foundation which isthreadedly connected to the implants;

FIG. 13 is an exploded perspective view of a threaded dental implant andinternally threaded upper locking cap.

FIG. 14 is a perspective view of a threaded implant wherein the cap isthreadedly connected to the implant and is in the process of beingsecured thereto utilizing a curable resin.

FIG. 15 is an elevational view of a spheroidal headed locking cap.

FIG. 16 is a partial cut away view of the locking cap of FIG. 15, takenalong lines 16-16.

FIG. 17 is a top plan view of the spheroidal headed locking cap.

FIG. 18 A-C are elevational front and side views, respectively, and atop view, of an ovoidal locking cap.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As described herein, the various rigid structural components shown inthe drawings are fabricated from, for example, titanium, stainlesssteel, and/or any other suitable dental implant material which canwithstand functional loads and support crowns, bridge segments, or thecomplete replacement of teeth with tooth forms/syntheticteeth/artificial teeth.

A model of a patient's jaw ridge R is shown in FIGS. 1 and 1 a,including implanted into the jawbone ridge a pair of the guide, orindexing, pins 2 in the posterior-most portions of the model, and aseries of implant screw type retention pins 5. Each of the retentionpins in this embodiment, has a flattened dome-shaped, or spheroidal,head 9, and a narrower neck 10 and threaded shank 20, extending into thejawbone. Intermediate the shank and neck is a flange 22 having adistally facing platform 22A. The combination of the neck 10 and head 9provides an undercut surface for retention and the platform 22A a firmsupport for the denture. In addition, closely surrounding the neck 10there may be employed a removable elastic band 7, which can be utilizedto vary the degree of any undercut effect by reducing or increasing theeffective diameter of the shank to the needs of the patient.

The spheroidal or ovoidal headed implant caps can be used for a singletooth prosthesis (FIG. 11) or as part of a bridge denture, with othersuch implants. As shown specifically in FIG. 12, and described morefully in the context of the Prior Case, another preferred embodiment ofthe holding implant screw 94, 18 has, at one end, a relatively longself-tapping threaded shaft 20. In use, an opening is made through anysoft dental tissue, e.g., gums, overlying the jawbone, and the implantscrew 18 is screwed into the hard dental tissue. The implant screw 18has various advantageous features, such as a flange having a flatsurface 22A on a first side adjacent to which modular components arepositioned and supported, and having a tapered smooth portion 22B on asecond side facing the dental tissue from which the threaded shaft 20extends. The threads preferably do not extend the full length of theshaft 20, such that a substantially smooth, unthreaded portion ispreferably present immediately adjacent the tapered portion 22B. Inaddition, this embodiment of the implant screw 18 includes a drivingportion 24 which, in this example, is a flat polygonal extension, havinga rectangular longitudinal cross-section. The driving portion 24 isadapted to engage a tool, such as a socket wrench bit. This is morefully set out in the Prior Case, incorporated herein. It is understoodthat the driving portion need not be in the specific shape shown, andmay be polygonal concavity or extension, to engage compatible toolsknown in the art.

The preferred embodiment of the slender holding implant screw 94, asshown in FIG. 13, includes at the protruding longitudinal end,prosthesis connecting member 26, for attaching modular prosthesiscomponents thereto. As shown, the prosthesis connecting member 26 isexternally threaded for receiving an internally threaded cap 109; forremovably but rigidly connecting the implant screw to the splint.

As shown specifically in FIG. 13, and described more fully in the “PriorCase”, a preferred embodiment of the implant screw 8 has at one end arelatively long self-tapping threaded shaft 20 and an adjacent shortersmooth cylindrical shaft 21. A flange 22 is provided longitudinallyadjacent the smooth portion of the shaft 21, distal of the threadedportion, and includes a smooth tapered portion immediately adjacent theshaft flowing outwardly to a flat surface substantially perpendicular tothe axis of the shaft and facing away from the shaft. A driving portionhaving a substantially polygonal cross-section extends longitudinallyfrom the flat flange surface portion 22. An externally threadedprosthesis connecting member 26 extends axially from the driving portion24 in a direction away from the shaft 20. The non-adherent locking screwcap 109 of this invention is shown in a position in FIG. 13 adjacent thethreaded connector 26, and in FIG. 14 screwed onto the threadedconnector 26.

The locking cap 109 comprises an annular, open-ended skirt portion 129,having a generally cylindrical outer circumferential surface. A pair ofcircumferential apertures 110 are formed therethrough, so as to extendcompletely through the wall of the skirt 129.

At the distal end of the locking cap 109 is a substantially spheroidalhead portion 119 having radial, transversely extending slots 120 formedat diametrically opposed edges of the circumference of the spheroidalhead. A narrower neck portion 116 is located intermediate the top of theskirt portion 129 which is defined by a relatively flat surface 121, andthe spheroidal head 119. A central opening, defined by an internallythreaded wall surface 115 extends completely through the spheroid head119 and the neck portion 116, to the interior of the skirt portion.

An alternative locking cap 209 is shown in FIGS. 18 A-C. At the distalend of the locking cap 209 is a substantially ovoidal head portion 219having slots 120 preferably extending along the major circumference ofthe ovoidal head, as shown. The remaining aspects of this cap are asdescribed above.

The locking caps 109, 209 of this invention are preferably molded from apolymer of the types commonly used for placement in the mouth, bydentists, such as the polyacetal resin Delrin, utilizing eitherco-polymer grades or homo-polymer grades. Other useful materials includedental grades of nylon or polysulfone. Other suitable dental resinshaving the desired mechanical strength may also be utilized.

The relatively soft locking cap 109 made of a polymeric material ispreferably used at least during the preliminary period after the implantis first affixed, when it is desired to provide an immediate replacementor splint to both hold a plurality of such implants in place and toprovide the patient with at least an immediate replacement for themissing teeth, even though it is not one that may be maintained on apermanent basis. After the implants and bone have healed and becomefirmly secured, the permanent prosthesis can then be fitted. As thefitting of a permanent prosthesis often requires several trials, whenthe prosthesis must be removed, refitted and replaced, the use of a hardmetal cap during this period could result in some damage to the metalimplants. By utilizing the relatively soft resin cap, the likelihood ofany damage occurring to the implant, from a cross threading or the like,is greatly reduced, if not wholly eliminated.

To further enhance the effectiveness of these caps, and to avoid theircoming loose during this period, the caps can be initially filled with acurable dental resin in the cup formed by the skirt, preferably of theauto-cure or light cure type, and the cap is then applied to thethreaded top portion of the implant and screwed down, while the excessresin from the skirt portion is squeezed out the top of the cap throughthe opening defined by the surface 115.

As noted, the apertures 110 can be covered by a removable siliconesleeve 130 during curing, having sufficient elasticity to be able to bereadily removed after the resin is set, if desired. The dental resin isgenerally not adherent to the silicone so the resin does not interferewith the removal of the sleeve. Any excess uncured resin which exudesfrom the top of the cap during the process of its being screwed on tothe implant can be readily wiped-off before it hardens.

When the resin in the skirt is hardened, it surrounds the polygonaldrive member 24 and extends into the apertures. This preventsinadvertent rotation of the cap when subjected to various stresses inthe mouth. However, when the cap and resin are subjected to torque bythe application of e.g., the U-shaped driver, on the slots 120,220, thehardened resin in the apertures will press against the narrow portions117 separating the apertures; these narrow portions in the skirt 117 arerelatively weak, so that when torque is applied to the head of the resincap the narrow portions with rupture. The cured dental resin, within theapertures of the skirt, pressing against these narrow portions betweenthe apertures, will cause them to rupture upon the application of areasonable torsional force, e.g. by utilizing a “U” shaped driver in theopposing slots 120,220. The intermediate wall portions 117 can befurther weakened by machining out some material so they are not as thickin cross-section as the remaining portion of the skirt wall 129. The topportion of the cap can be removed when it is unscrewed. The lower skirtsurrounding the driving portion 24 can be readily lifted out andremoved, exposing the exposed threaded connection 26, for attaching anew cap when the prosthesis is replaced by the dentist. This process canbe repeated several times as needed during the trials and fittings of acustomized prosthesis, without likelihood that the implant will bedamaged.

Prior to initially forming the splint, of whichever form, a mold of themouth showing the locations of the upper ends of the implants and theirshape, together with any indexing element 80 present on each implant, ismade using the usual dental impression material. A denture prosthesiscan be prepared from this mold, by known procedures, which will locatethe implant tops extending through the dental prosthesis. The concavityformed by the posterior indexing implants should be expanded to a largeropening to leave room for the jacket insert to be attached to thedenture. This initial foundation, formed from a relatively hard dentalresin, is then treated to remove material from the concave portionformed around the jaw ridge, to permit the molding and/or insertion of asofter more resilient dental resin liner, if desired.

This is not a part of this invention and merely provides the context forits use. This context is described more fully in a prior publishedapplication by the applicant (U.S. Patent Publication 2004/0166476-A1).

The use of the caps of this invention does not interfere withconventional molding techniques for dentures and, thus, allows dentistsand dental laboratories to continue with their usual practice whenforming a permanent denture prosthesis.

The above disclosure sets forth preferred embodiments of the presentinvention. Only the following claims fully define the invention:

The following invention is claimed:
 1. A method of fitting a resilientlylined rigid prosthetic denture, of the type removably secured topermanently implanted dental support posts embedded into a patient'sjaw, where the support posts each include a shank secured into thepatient's jaw and a head portion extending outwardly longitudinally fromthe shank and beyond the patients jaw surface, the head portioncomprising a neck extending outwardly above the jaw surface and a capsecured to the outward end of the neck portion and extending from theneck portion, the cap is of a generally elongated, or ellipsoidal shapefrom a top view the method comprising the steps of: molding a dentureprosthesis foundation, to form a dental prosthesis, including a concaveunder surface intended to fit over and around the jaw ridge, thefoundation being formed from a relatively hard dental resin, the harddental resin defining the concave portion being formed to provide spacefor the insertion, and the molding, of a softer, more resilient dentalresin liner within the concave portion, the molding being carried out ona form selected from the patient's jaw ridge or a molded form made ofthe patient's jaw ridge, the form including the head portion and caps ofeach implanted post in the mouth of the patient, inserting a curable,softer, more resilient dental resin into the concave portion, removablyplacing the denture foundation containing the curable, softer, moreresilient dental resin, onto the form, and allowing the curableresilient resin to cure and set, so as to form a suitable seal betweenthe cured resilient resin and the sides of the jaw ridge and around thecaps, resulting in a removable but sealably secure denture in the mouthof the patient.
 2. The method of claim 1 wherein the neck is relativelyslender and the ellipsoidal cap extends transversely from the neck. 3.The method of claim 1 wherein the material of construction of the cap isa material that is non-adherent to the soft, resilient lining of thedenture.
 4. The method of claim 1 wherein the cap is ellipsoidal inshape and is rotated so as to be parallel to or transverse to the axisof the concave underside of the denture, when the soft dental resin ismolded, so as to form a tight fit in the resilient material.
 5. A methodof fitting a resiliently lined rigid prosthetic denture, of the typeremovably secured to permanently implanted dental support posts embeddedinto a patient's jaw, where the support posts each include a shanksecured into the patient's jaw and a head portion extending outwardlylongitudinally from the shank and beyond the patients jaw surface, thehead portion comprising a neck extending outwardly above the jaw surfaceand a cap secured to the outward end of the neck portion and extendingfrom the neck portion, the cap is of a generally flattened dome-shape,spheroidal or elongated, or ellipsoidal shape, the caps being covered bya jacket formed of a flexible, resilient dental polymer the methodcomprising the steps of: molding a denture prosthesis foundation to forma dental prosthesis including a concave under surface intended to fitover and around the jaw ridge, the foundation being formed from arelatively hard dental resin, the hard dental resin defining the concaveportion being formed to provide space for the insertion, and themolding, of a softer, more resilient dental resin liner within theconcave portion, the molding being carried out on a form selected fromthe patient's jaw ridge or a molded form made from the patient's jawridge, the form including the jacketed cap of each implanted post in themouth of the patient, inserting a curable, softer, more resilient dentalresin into the concave portion, removably placing the denture foundationcontaining the curable, softer, more resilient dental resin, onto theform, and allowing the curable, resilient resin to cure and set, so asto form a suitable seal between the cured resilient resin and the sidesof the jaw ridge and around the caps, resulting in a removable butsealably secure denture in the mouth of the patient.
 6. The method ofclaim 5 wherein the jacket is formed of a silicone polymer.
 7. Themethod of claim 5 wherein the cap presents a generally circular shapewhen view from above.
 8. The method of claim 5 wherein the jacketsremain in the cured resilient resin when the denture is removed from theform.